The case for using animals in medical research

The Zika virus has been linked to severe birth defects, including microcephaly, since it surfaced in Brazil about a year ago.

Frankie L. Trull

Ground zero in the fight against Zika is now at the National Institutes of Health in suburban Washington.

NIH scientists are testing a vaccine that could prevent people from acquiring the virus. Trials of a similar vaccine successfully immunized monkeys.

Good news, right? Apparently not. Earlier this month, at another NIH facility just 3 miles away, a different group of scientists gathered to debate whether it's appropriate to conduct medical research — like the kind that's delivered this promising Zika vaccine — in primates at all.

The NIH workshop on Sept. 7 convened experts in science, policy, ethics and animal welfare and was conducted, in part, in response to congressional interest in reviewing how research is conducted.

That question shouldn't even need to be asked. Research in nonhuman primates has been essential to the development of cures for everything from polio to forms of cancer. And it's our best hope for cures for modern scourges like Zika, Alzheimer's and Parkinson's.

Scientists use nonhuman primates to determine the safety and efficacy of potential vaccines or treatments. Since primates share as much as 98 percent of their genetic code with humans, they offer an excellent approximation of the human body's complexity.

Jeff Miller / Associated Press

Rhesus monkeys are shown at the Wisconsin National Primate Research Center at the University of Wisconsin-Madison.

Rhesus monkeys are shown at the Wisconsin National Primate Research Center at the University of Wisconsin-Madison.

(Jeff Miller / Associated Press)

Work with primates comprises less than 1 percent of all animal research. But it's had an outsized impact on medical progress.

Consider the polio vaccine. By the early 1950s, poliovirus had devastated the United States, infecting over 20,000 Americans — many of them children — each year. The virus was too small to be seen by the methods available at the time, so researchers like Albert Sabin depended on monkeys for testing.

That led to a cure. Sabin eventually developed an oral polio vaccine that replaced Jonas Salk's.

Years later, Sabin noted that his use of monkeys was critical to his success. "Without the use of animals and of human beings, it would have been impossible to acquire the important knowledge needed to prevent much suffering and premature death not only among humans but also among animals," Sabin wrote.

Researchers are now using the poliovirus in monkeys to battle glioblastoma, a deadly form of brain cancer that can double in size every two weeks and can be fatal within months.

Research in monkeys has already yielded stunning results. Scientists injected a modified poliovirus that attached itself to cancer cells in the monkey's brain. The monkey's body recognized the virus as dangerous and began to attack it, killing the cancer cells in the process.

This procedure has advanced to human trials; already, two patients have seen their glioblastoma go into full remission. They can thank research in monkeys for their new lease on life.

"This is the most promising therapy I've seen in my career. Period," said Dr. Henry Friedman, an internationally renowned neuro-oncologist, about the treatment during a "60 Minutes" segment in 2015.

Primate research has been the bridge from the lab to the clinic for a number of groundbreaking treatments, including vaccines for mumps, measles, yellow fever, anthrax and hepatitis B.

Yet critics of animal research claim that such testing is unnecessary. They argue that computer models can effectively replace animal models.

They're delusional. Consider, for example, the complexity of the human brain, which has about 100 billion neurons and 1 quadrillion synapses.

In 2014, researchers in Japan attempted to simulate brain activity by using a supercomputer with over 700,000 processor cores. It took the computers 40 minutes of whirring to effectively replicate what the brain does in one second.

Primates, on the other hand, can effectively imitate human brains. And that fact has led to numerous treatments.

Researchers in the 1970s closely studied primates' basal ganglia — the part of the brain responsible for movement. These insights led to the development of a treatment for Parkinson's disease, which slowly robs people of their motor control. That treatment, called deep brain stimulation, safely blocks certain electronic signals from the brain to alleviate some of the disease's worst effects.

If researchers were barred from working with primate models, they'd have only one recourse — giving untested drugs and therapies to humans. That's not just illegal but unethical. And it'd essentially halt a significant amount of medical research.

Research in primates has worked before and will work in the years to come. As Francis Collins, director of the NIH, recently noted, "Research with nonhuman primates is an essential component of the NIH mission."

Let's hope those debating the future of primate research models at the NIH remember that.

Frankie L. Trull is president of the Foundation for Biomedical Research.